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Posted Sun Jun 3, 2018 8:38 PM
Posted Sun Jun 3, 2018 10:46 PM
I recently got an oppurtunity to repair a busted 4000. It appears to work well now with 128K and 512K SRAM. So it looks fixed and all but I cannot for the life of me figure out how to split the card into two different CRU addresses on the TI.
The manual is pretty non specific and vague on this topic.
If anyone out there has this knowledge then please drop in.
Never done it myself as I don't own a 4000. I played around with one for a short while so I took a look at the attached manual. See page 13.
The last few sentences of the last paragraph are important for setting the two CRU addresses and how they are tied to each of the two memory segments. You must have a 32K chip installed in place of the 8k chip, the jumper must be set to 32k. Use the TI configuration, not Geneve. Check the position of J2. Theoretically, by selecting two CRU addresses (watch for the overlap) you'll get two visible for formatting.
Posted Mon Jun 4, 2018 7:23 AM
This is also done with two 4000's in the same P-Box for a total of 10meg storage. One card populated with 128k chips and a second card populated with 512k chips. My grey matter isn't what it used to be but I think it requires U1 and U2 to be populated with 74HC154 also SW1 must be set for this but I'm working and have nothing in front of me to go by but I think I remember SW1 settings in the 4000 manual.
10 megs of RAM disk is a beautiful thing.
Posted Mon Jun 4, 2018 8:01 AM
Posted Mon Jun 4, 2018 9:29 AM
I have a huge supply of the .300 74HCT154s (skinny-DIP). . .they are generally unobtainium lately, but I found a source that would produce and sell them (these are newly manufactured chips from an authorized OEM) for a reasonable price, so I bought some (I think it was something in the vicinity of 1,500 chips as a minimum order, but the price was right, so it was worth it).
Posted Mon Jun 4, 2018 4:15 PM
The card as it sets is pop'd with 128k SRAM and is fully loaded and works.
When I switch in 512k's it still works and I can see 5 meg (I only have 10.)
I can set the jumpers by the paperwork for dual disk operation ( using both flavors of RAM ) but stall out right there. I'm not sure if it is a lingering HW, SW or user issue.
What happens does it lock up or only show one CRU? Maybe you have to turn the switch OFF until you run CFG. You got the 32K jumper set for 32K not 8k, and two CRU selections based on manual. I was gonna suggest swapping the memory addressing chips to see if one of them has a bad input/output. If you swap and don't get the 5meg then you have trouble.
Posted Mon Jun 4, 2018 7:39 PM
Posted Mon Jun 4, 2018 7:45 PM
Can ya snap a picture or two of the card itself as configured? (wait two minutes -grin-)
Posted Mon Jun 4, 2018 8:50 PM
Posted Tue Jun 5, 2018 5:13 AM
With the split memory jumper set I get half the memory displayed. Loads just fine and I can partion disks. This is what makes me think I am missing something. Is there a special CFG program for this card or more likely some dance moves I'm missing ?
You are hitting the "Next" key while in the config program so you set up more than one address right? Each address gets formatted not just one address, right?
Posted Tue Jun 5, 2018 9:33 AM
That may be the move Richard, thanks.
Do you happen to know if the dip switch needs to have more than one selection ?
Yes, SW1 will have two selected "ON" but unfortunately I'm working and have nothing in front of me to rattle the old grey matter. You will know when SW1 is set right when you are in CONFIG and press the "N" next key because repeated pressing will show what both addresses are.
Posted Tue Jun 5, 2018 1:20 PM
Sent you a reply to your picture PM with a potential solution.
What's the potential solution?
Posted Tue Jun 5, 2018 5:46 PM
Posted Tue Jun 5, 2018 5:59 PM
I understand this card will go in a Geneve as a boot device. I think I know that this limits the boot drive in size. Does this preclude maxing the card to 8 MB ?
MDOS 7.00 contains the routines needed to access the ramdisk as a hard drive and a boot drive. I haven't finished my work on it though so the best you can do for now is split the RAMdisk into two segments and use CRUs available to MDOS. There is a problem with disk formats above 800k so using the old FORM v1.23 to prep the ramdisks is preferred.
Posted Tue Jun 5, 2018 6:12 PM
Posted Tue Jun 5, 2018 6:21 PM
The physical memory can be up to 4mb for each CRU address. FORM v1.23 will only format up to 800k of the 4MB. FORM3MEG will format each side up to 3.2MB with the risk of file corruption. Yea, Geneve is a little different in how the disks were implemented back when a small 192K RAMdisk was very expensive.
MDOS 7 resolves this by allowing you to format all 8MB as one large hard drive, minus 400K (or 800K) for a floppy partition used to boot the OS.,
Posted Tue Jun 5, 2018 7:13 PM
Posted Tue Jun 5, 2018 10:01 PM
Theoretically the same. Depends whether or not I can support two CRU addresses in the final release
new configuration. Right now I have two ramdisks in the same system, each with a floppy disk partition and hard drive partition. The same can be emulated with a 4000 in the dual ramdisk configuration by all accounts.
Edited by InsaneMultitasker, Tue Jun 5, 2018 10:02 PM.
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